/*
 * Copyright 2002-2006 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.jtracc.util;

import java.lang.reflect.Array;
import java.util.Arrays;

/**
 * Miscellaneous object utility methods. Mainly for internal use within the
 * framework; consider Jakarta's Commons Lang for a more comprehensive suite
 * of object utilities.
 *
 * @author Juergen Hoeller
 * @author Keith Donald
 * @author Rod Johnson
 * @author Rob Harrop
 * @author Alex Ruiz
 * @see org.apache.commons.lang.ObjectUtils
 * @since 19.03.2004
 */
public abstract class ObjectUtils
{

    private static final int INITIAL_HASH = 7;
    private static final int MULTIPLIER = 31;

    private static final String EMPTY_STRING = "";
    private static final String NULL_STRING = "null";
    private static final String ARRAY_START = "{";
    private static final String ARRAY_END = "}";
    private static final String EMPTY_ARRAY = ARRAY_START + ARRAY_END;
    private static final String ARRAY_ELEMENT_SEPARATOR = ", ";


    /**
     * Return whether the given throwable is a checked exception:
     * that is, neither a RuntimeException nor an Error.
     *
     * @param ex the throwable to check
     *
     * @return whether the throwable is a checked exception
     *
     * @see java.lang.Exception
     * @see java.lang.RuntimeException
     * @see java.lang.Error
     */
    public static boolean isCheckedException(Throwable ex)
    {
        return !( ex instanceof RuntimeException || ex instanceof Error );
    }

    /**
     * Check whether the given exception is compatible with the exceptions
     * declared in a throws clause.
     *
     * @param ex                 the exception to checked
     * @param declaredExceptions the exceptions declared in the throws clause
     *
     * @return whether the given exception is compatible
     */
    public static boolean isCompatibleWithThrowsClause(Throwable ex, Class[] declaredExceptions)
    {
        if (!isCheckedException( ex ))
        {
            return true;
        }
        if (declaredExceptions != null)
        {
            for (int i = 0; i < declaredExceptions.length; i++)
            {
                if (declaredExceptions[i].isAssignableFrom( ex.getClass() ))
                {
                    return true;
                }
            }
        }
        return false;
    }

    /**
     * Return whether the given array is empty: that is, <code>null</code>
     * or of zero length.
     *
     * @param array the array to check
     */
    public static boolean isEmpty(Object[] array)
    {
        return ( array == null || array.length == 0 );
    }

    /**
     * Append the given Object to the given array, returning a new array
     * consisting of the input array contents plus the given Object.
     *
     * @param array the array to append to (can be <code>null</code>)
     * @param obj   the Object to append
     *
     * @return the new array (of the same component type; never <code>null</code>)
     */
    public static Object[] addObjectToArray(Object[] array, Object obj)
    {
        Class compType = Object.class;
        if (array != null)
        {
            compType = array.getClass().getComponentType();
        }
        else if (obj != null)
        {
            compType = obj.getClass();
        }
        int newArrLength = ( array != null ? array.length + 1 : 1 );
        Object[] newArr = (Object[]) Array.newInstance( compType, newArrLength );
        if (array != null)
        {
            System.arraycopy( array, 0, newArr, 0, array.length );
        }
        newArr[newArr.length - 1] = obj;
        return newArr;
    }

    /**
     * Convert a primitive array to an object array of primitive wrapper objects.
     *
     * @param primitiveArray the primitive array
     *
     * @return the object array
     *
     * @throws IllegalArgumentException if the parameter is not a primitive array
     */
    public static Object[] toObjectArray(Object primitiveArray)
    {
        if (primitiveArray == null)
        {
            return new Object[0];
        }
        Class clazz = primitiveArray.getClass();
        if (!clazz.isArray() || !clazz.getComponentType().isPrimitive())
        {
            throw new IllegalArgumentException( "The specified parameter is not a primitive array" );
        }
        int length = Array.getLength( primitiveArray );
        if (length == 0)
        {
            return new Object[0];
        }
        Class wrapperType = Array.get( primitiveArray, 0 ).getClass();
        Object[] newArray = (Object[]) Array.newInstance( wrapperType, length );
        for (int i = 0; i < length; i++)
        {
            newArray[i] = Array.get( primitiveArray, i );
        }
        return newArray;
    }

    //---------------------------------------------------------------------
    // Convenience methods for content-based equality/hash-code handling
    //---------------------------------------------------------------------

    /**
     * Determine if the given objects are equal, returning <code>true</code>
     * if both are <code>null</code> or <code>false</code> if only one is
     * <code>null</code>.
     * <p>Compares arrays with <code>Arrays.equals</code>, performing an equality
     * check based on the array elements rather than the array reference.
     *
     * @param o1 first Object to compare
     * @param o2 second Object to compare
     *
     * @return whether the given objects are equal
     *
     * @see java.util.Arrays#equals
     */
    public static boolean nullSafeEquals(Object o1, Object o2)
    {
        if (o1 == o2)
        {
            return true;
        }
        if (o1 == null || o2 == null)
        {
            return false;
        }
        if (o1.equals( o2 ))
        {
            return true;
        }
        if (o1 instanceof Object[] && o2 instanceof Object[])
        {
            return Arrays.equals( (Object[]) o1, (Object[]) o2 );
        }
        if (o1 instanceof boolean[] && o2 instanceof boolean[])
        {
            return Arrays.equals( (boolean[]) o1, (boolean[]) o2 );
        }
        if (o1 instanceof byte[] && o2 instanceof byte[])
        {
            return Arrays.equals( (byte[]) o1, (byte[]) o2 );
        }
        if (o1 instanceof char[] && o2 instanceof char[])
        {
            return Arrays.equals( (char[]) o1, (char[]) o2 );
        }
        if (o1 instanceof double[] && o2 instanceof double[])
        {
            return Arrays.equals( (double[]) o1, (double[]) o2 );
        }
        if (o1 instanceof float[] && o2 instanceof float[])
        {
            return Arrays.equals( (float[]) o1, (float[]) o2 );
        }
        if (o1 instanceof int[] && o2 instanceof int[])
        {
            return Arrays.equals( (int[]) o1, (int[]) o2 );
        }
        if (o1 instanceof long[] && o2 instanceof long[])
        {
            return Arrays.equals( (long[]) o1, (long[]) o2 );
        }
        if (o1 instanceof short[] && o2 instanceof short[])
        {
            return Arrays.equals( (short[]) o1, (short[]) o2 );
        }
        return false;
    }

    /**
     * Return as hash code for the given object; typically the value of
     * <code>{@link Object#hashCode()}</code>. If the object is an array,
     * this method will delegate to any of the <code>nullSafeHashCode</code>
     * methods for arrays in this class. If the object is <code>null</code>,
     * this method returns 0.
     *
     * @see #nullSafeHashCode(Object[])
     * @see #nullSafeHashCode(boolean[])
     * @see #nullSafeHashCode(byte[])
     * @see #nullSafeHashCode(char[])
     * @see #nullSafeHashCode(double[])
     * @see #nullSafeHashCode(float[])
     * @see #nullSafeHashCode(int[])
     * @see #nullSafeHashCode(long[])
     * @see #nullSafeHashCode(short[])
     */
    public static int nullSafeHashCode(Object obj)
    {
        if (obj == null)
        {
            return 0;
        }
        if (obj instanceof Object[])
        {
            return nullSafeHashCode( (Object[]) obj );
        }
        if (obj instanceof boolean[])
        {
            return nullSafeHashCode( (boolean[]) obj );
        }
        if (obj instanceof byte[])
        {
            return nullSafeHashCode( (byte[]) obj );
        }
        if (obj instanceof char[])
        {
            return nullSafeHashCode( (char[]) obj );
        }
        if (obj instanceof double[])
        {
            return nullSafeHashCode( (double[]) obj );
        }
        if (obj instanceof float[])
        {
            return nullSafeHashCode( (float[]) obj );
        }
        if (obj instanceof int[])
        {
            return nullSafeHashCode( (int[]) obj );
        }
        if (obj instanceof long[])
        {
            return nullSafeHashCode( (long[]) obj );
        }
        if (obj instanceof short[])
        {
            return nullSafeHashCode( (short[]) obj );
        }
        return obj.hashCode();
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(Object[] array)
    {
        if (array == null)
        {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++)
        {
            hash = MULTIPLIER * hash + nullSafeHashCode( array[i] );
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(boolean[] array)
    {
        if (array == null)
        {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++)
        {
            hash = MULTIPLIER * hash + hashCode( array[i] );
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(byte[] array)
    {
        if (array == null)
        {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++)
        {
            hash = MULTIPLIER * hash + array[i];
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(char[] array)
    {
        if (array == null)
        {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++)
        {
            hash = MULTIPLIER * hash + array[i];
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(double[] array)
    {
        if (array == null)
        {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++)
        {
            hash = MULTIPLIER * hash + hashCode( array[i] );
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(float[] array)
    {
        if (array == null)
        {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++)
        {
            hash = MULTIPLIER * hash + hashCode( array[i] );
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(int[] array)
    {
        if (array == null)
        {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++)
        {
            hash = MULTIPLIER * hash + array[i];
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(long[] array)
    {
        if (array == null)
        {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++)
        {
            hash = MULTIPLIER * hash + hashCode( array[i] );
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(short[] array)
    {
        if (array == null)
        {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++)
        {
            hash = MULTIPLIER * hash + array[i];
        }
        return hash;
    }

    /**
     * Return the same value as <code>{@link Boolean#hashCode()}</code>.
     *
     * @see Boolean#hashCode()
     */
    public static int hashCode(boolean bool)
    {
        return bool ? 1231 : 1237;
    }

    /**
     * Return the same value as <code>{@link Double#hashCode()}</code>.
     *
     * @see Double#hashCode()
     */
    public static int hashCode(double dbl)
    {
        long bits = Double.doubleToLongBits( dbl );
        return hashCode( bits );
    }

    /**
     * Return the same value as <code>{@link Float#hashCode()}</code>.
     *
     * @see Float#hashCode()
     */
    public static int hashCode(float flt)
    {
        return Float.floatToIntBits( flt );
    }

    /**
     * Return the same value as <code>{@link Long#hashCode()}</code>.
     *
     * @see Long#hashCode()
     */
    public static int hashCode(long lng)
    {
        return (int) ( lng ^ ( lng >>> 32 ) );
    }

    //---------------------------------------------------------------------
    // Convenience methods for content-based toString output
    //---------------------------------------------------------------------

    /**
     * Return a String representation of the specified Object.
     * <p>Returns {@link #NULL_STRING the String 'null'} if <code>obj</code> is
     * <code>null</code>.
     *
     * @param obj the object whose String representation to return
     *
     * @return a String representation of <code>obj</code>
     */
    public static String nullSafeToString(Object obj)
    {
        if (obj == null)
        {
            return NULL_STRING;
        }
        if (obj instanceof String)
        {
            return (String) obj;
        }
        if (obj instanceof Object[])
        {
            return nullSafeToString( (Object[]) obj );
        }
        if (obj instanceof boolean[])
        {
            return nullSafeToString( (boolean[]) obj );
        }
        if (obj instanceof byte[])
        {
            return nullSafeToString( (byte[]) obj );
        }
        if (obj instanceof char[])
        {
            return nullSafeToString( (char[]) obj );
        }
        if (obj instanceof double[])
        {
            return nullSafeToString( (double[]) obj );
        }
        if (obj instanceof float[])
        {
            return nullSafeToString( (float[]) obj );
        }
        if (obj instanceof int[])
        {
            return nullSafeToString( (int[]) obj );
        }
        if (obj instanceof long[])
        {
            return nullSafeToString( (long[]) obj );
        }
        if (obj instanceof short[])
        {
            return nullSafeToString( (short[]) obj );
        }
        return obj.toString();
    }

    /**
     * Return a String representation of the contents of the specified array. The
     * String representation consists of a list of the array's elements, enclosed
     * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
     * the characters <code>", "</code> (a comma followed by a space). Returns
     * <code>"null"</code> if <code>array</code> is <code>null</code>.
     *
     * @param array the array whose String representation to return
     *
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(Object[] array)
    {
        if (array == null)
        {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0)
        {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++)
        {
            if (i == 0)
            {
                buffer.append( ARRAY_START );
            }
            else
            {
                buffer.append( ARRAY_ELEMENT_SEPARATOR );
            }
            buffer.append( String.valueOf( array[i] ) );
        }
        buffer.append( ARRAY_END );
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array. The
     * String representation consists of a list of the array's elements, enclosed
     * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
     * the characters <code>", "</code> (a comma followed by a space). Returns
     * <code>"null"</code> if <code>array</code> is <code>null</code>.
     *
     * @param array the array whose String representation to return
     *
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(boolean[] array)
    {
        if (array == null)
        {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0)
        {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++)
        {
            if (i == 0)
            {
                buffer.append( ARRAY_START );
            }
            else
            {
                buffer.append( ARRAY_ELEMENT_SEPARATOR );
            }

            buffer.append( array[i] );
        }
        buffer.append( ARRAY_END );
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array. The
     * String representation consists of a list of the array's elements, enclosed
     * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
     * the characters <code>", "</code> (a comma followed by a space). Returns
     * <code>"null"</code> if <code>array</code> is <code>null</code>.
     *
     * @param array the array whose String representation to return
     *
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(byte[] array)
    {
        if (array == null)
        {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0)
        {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++)
        {
            if (i == 0)
            {
                buffer.append( ARRAY_START );
            }
            else
            {
                buffer.append( ARRAY_ELEMENT_SEPARATOR );
            }
            buffer.append( array[i] );
        }
        buffer.append( ARRAY_END );
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array. The
     * String representation consists of a list of the array's elements, enclosed
     * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
     * the characters <code>", "</code> (a comma followed by a space). Returns
     * <code>"null"</code> if <code>array</code> is <code>null</code>.
     *
     * @param array the array whose String representation to return
     *
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(char[] array)
    {
        if (array == null)
        {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0)
        {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++)
        {
            if (i == 0)
            {
                buffer.append( ARRAY_START );
            }
            else
            {
                buffer.append( ARRAY_ELEMENT_SEPARATOR );
            }
            buffer.append( "'" ).append( array[i] ).append( "'" );
        }
        buffer.append( ARRAY_END );
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array. The
     * String representation consists of a list of the array's elements, enclosed
     * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
     * the characters <code>", "</code> (a comma followed by a space). Returns
     * <code>"null"</code> if <code>array</code> is <code>null</code>.
     *
     * @param array the array whose String representation to return
     *
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(double[] array)
    {
        if (array == null)
        {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0)
        {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++)
        {
            if (i == 0)
            {
                buffer.append( ARRAY_START );
            }
            else
            {
                buffer.append( ARRAY_ELEMENT_SEPARATOR );
            }

            buffer.append( array[i] );
        }
        buffer.append( ARRAY_END );
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array. The
     * String representation consists of a list of the array's elements, enclosed
     * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
     * the characters <code>", "</code> (a comma followed by a space). Returns
     * <code>"null"</code> if <code>array</code> is <code>null</code>.
     *
     * @param array the array whose String representation to return
     *
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(float[] array)
    {
        if (array == null)
        {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0)
        {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++)
        {
            if (i == 0)
            {
                buffer.append( ARRAY_START );
            }
            else
            {
                buffer.append( ARRAY_ELEMENT_SEPARATOR );
            }

            buffer.append( array[i] );
        }
        buffer.append( ARRAY_END );
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array. The
     * String representation consists of a list of the array's elements, enclosed
     * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
     * the characters <code>", "</code> (a comma followed by a space). Returns
     * <code>"null"</code> if <code>array</code> is <code>null</code>.
     *
     * @param array the array whose String representation to return
     *
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(int[] array)
    {
        if (array == null)
        {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0)
        {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++)
        {
            if (i == 0)
            {
                buffer.append( ARRAY_START );
            }
            else
            {
                buffer.append( ARRAY_ELEMENT_SEPARATOR );
            }
            buffer.append( array[i] );
        }
        buffer.append( ARRAY_END );
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array. The
     * String representation consists of a list of the array's elements, enclosed
     * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
     * the characters <code>", "</code> (a comma followed by a space). Returns
     * <code>"null"</code> if <code>array</code> is <code>null</code>.
     *
     * @param array the array whose String representation to return
     *
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(long[] array)
    {
        if (array == null)
        {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0)
        {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++)
        {
            if (i == 0)
            {
                buffer.append( ARRAY_START );
            }
            else
            {
                buffer.append( ARRAY_ELEMENT_SEPARATOR );
            }
            buffer.append( array[i] );
        }
        buffer.append( ARRAY_END );
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array. The
     * String representation consists of a list of the array's elements, enclosed
     * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
     * the characters <code>", "</code> (a comma followed by a space). Returns
     * <code>"null"</code> if <code>array</code> is <code>null</code>.
     *
     * @param array the array whose String representation to return
     *
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(short[] array)
    {
        if (array == null)
        {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0)
        {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++)
        {
            if (i == 0)
            {
                buffer.append( ARRAY_START );
            }
            else
            {
                buffer.append( ARRAY_ELEMENT_SEPARATOR );
            }
            buffer.append( array[i] );
        }
        buffer.append( ARRAY_END );
        return buffer.toString();
    }

    /**
     * Return a String representation of an object's overall identity.
     *
     * @param obj the object (may be <code>null</code>)
     *
     * @return the object's identity as String representation,
     *         or <code>null</code> if the object was <code>null</code>
     */
    public static String identityToString(Object obj)
    {
        if (obj == null)
        {
            return EMPTY_STRING;
        }
        return obj.getClass().getName() + "@" + getIdentityHexString( obj );
    }

    /**
     * Return a hex String form of an object's identity hash code.
     *
     * @param obj the object
     *
     * @return the object's identity code in hex notation
     */
    public static String getIdentityHexString(Object obj)
    {
        return Integer.toHexString( System.identityHashCode( obj ) );
    }

    /**
     * Return a content-based String representation if <code>obj</code> is
     * not <code>null</code>; otherwise returns an empty <code>String</code>.
     * <p>Differs from <code>nullSafeToString</code> in that it returns an
     * empty String rather than "null" for a <code>null</code> value.
     *
     * @see #nullSafeToString(Object)
     */
    public static String getDisplayString(Object obj)
    {
        if (obj == null)
        {
            return EMPTY_STRING;
        }
        return nullSafeToString( obj );
    }

}
